Ferromagnet system for converting electric oscillations into acoustic vibrations or conversely



Jan. 16, 1934. A. A. BARTELINK FERROMAGNET SYSTEM FOR CONVERTINGELECTRIC OSCILLAT INTO ACOUSTIC VIBRATIONS OR CONVERSELY Flled Sept 11.1930 UNITED STATES PATENT OFF-ICE FERROMAGNET SYSTEM FOR CONVERTINGELECTREC OSCILLATIONS INTO ACOUSTIC VIBBATIONS OR CONVERSELY AlbertusAntony Bartelink, Eindhoven, Netherlands, assignor to Radio Corporationof America, a corporation of Delaware Application September 11, 1930,Serial No. 481,128, and in the Netherlands September 19, 1929 11 Claims.(Cl. 175339) This invention has reference to a terromagnet ferromagnetsystem according to the invention, 7 system of devices for convertingelectric oscillaand tions into acoustic vibrations or conversely, suchFigure 4 is a side view of this portion. as gramophones, loud speakers,microphones and Referring to Figures 1 and 2, the armature 4 is i thelike. arranged between two magnets 1 and 2 of an elec- It has beenproposed to damp the movement of tric pi p With p p c e a ature 4 thearmature in the magnetic field of such syshas a pcrtion 5 W ch S rves as1 holds! for a torus by applying rubber to the ends of the spinneedle 6clamped therein by means of a screw 7. dle of the armature. It has,however, been found The sp 8 to wh ch the armature is secured thateventually the composition of the rubber aland which is provided withconical ends is rotat- 5 ters, in that for example it becomes hard sothat ably arranged between two springs 9 secured by the movement of thearmature is interfered with screws 10 to the pole pieces 3. In order toavoid and is no longer suitable. any amount of latitude of the armaturethe A further limitation of the use of rubber in this Springs areprovided with apertures 11 in which case consists in that the air gapbetween'the arthe spindleends are journalled. mature and the pole piecesof the magnet is con- In the form of construction shown in Figures 3sequently not equally large with all the devices and 4 the springs 12between which the spindle made in the same manner. This is due to thefact 13 is rotatably arranged constitute two opposite that for thecorrect adjustment of the armature sides of a frame 14 which has its twoother sides 20 the ends of the spindle with the rubber areexlfisecuredby screws 16 to the pole pieces 17 of posed to some pressure. Thisresults in the rubthe magnet system not shown. ber being compressed inone case to an extent dif- For the purpose of illustrating the inventionferent from that inanother case so that like de it'has been deemedsuflicient to show only a porvices are all different as regards the sizeof the air tion of the armature and the pole pieces, as the 25 gap. Thisis objectionable in wholesale manuinvention resides in the manner inwhich the facture. spindle about which the armature vibrates, is Theinvention has for its object to obviate these d- It is to be d ood thata suitable and other disadvantages. coil is positioned so as to beinfluenced either According to the invention, for this purpose the bythe lines of force mu h the armature or 30 ends of the spindle of thearmature are arranged lines of force through e 01 both of the so as tobe resilient in the direction of the axis. poles of the magnet System-Such a ge- In one embodiment of t invention th Spin ments of coils arewell-known in the prior art and 11 is mounted between t springs whichmay do not require further description or illustrabe laminated ifdesired. Preferably, use will be tlon- 35 made f Spindles having conicalends In Order Inthe appended claims the term transducer to avoid anyundue amount of latitude of the aris u in s i its usual meaning tomature by wear of the ends of the spindle, the dslgnate y device takmgPower from one elec' Springs are provided with aper'tures m which thetrical, acoustical or mechanical system and furconical ends of thespindle are journalled. It is, msnfng power to another System of theSame 40 of course, obvious that consequently the rubber g f g g y i onthe ends'oi the spindle can be dispensed with I f c aim t and the placeof the armature between the pole i fl sys em i i pieces is fixed so thatthe air gaps of all the deg- E mi an im f nglu 5131.109. about vicesmade in the same manner are of equal size. W Sal d Elm-la 1. 1S afigppeto 'f' as In 0rd that the invention may be Clea-fly um cen er, an meansor resi iently supporting said s indle for mo nen derstood and readilycarried into effect some emg on1y Vex t the dlrecmon of Its bodiinentsthereof will be described with refer-- A ferromagnetic Stem for atransducer ence to the accompanying drawing, in W comprising anarmature, a rigid spindle forming 0 Flgllre 1 1s a bottom w of a f 01 a@911- the center of vibration of said armature. and

struction of an electric pick up with a. ferromagfle ibl means at theends f said Sundle for 116i y r 8 t0 the invention; permitting movementthereof in the direction of Figure 2 15 a side view of this portion; iti nly, Figure 3 tea bottom view of a portion of a dif- 3. Aferromagnetic system for a transducer ferent construction of an electricpick up with a comprising an armature, a rigid spindle rigidly Circonnected thereto, and means for supporting the ends of said spindle,said means permitting rotational and axial movement only of saidspindle.

4. A ferromagnetic system for a transducer comprising, an armature, aspindle forming the center of vibration therefor and flexible leafsprings cooperating with the ends of said spindle for permittingmovement thereof in the direction of its axis.

5. A transducer comprising a magnet system having .pole pieces, anarmature adapted to be vibrated between said pole pieces, a spindle onwhich said armature is mounted, and thin, flat springs supporting theends of said spindle in such a manner that the spindle is resilientlymounted in the direction of its axis.

6. A transducer comprising a magnet system having pole pieces, anarmature adapted .to be vibrated between said pole piece, a spindle onwhich said armature is mounted, a pair of thin, flat, flexible springmembers each of which is mounted at at least one end and provided withan aperture in which an end of the'spindle is seated, said springmembers mounting said spindle for flexible movement in the direction ofits axis only.

7. A transducer comprising a magnet system having pole pieces, anarmature adapted to vibrate between said pole pieces, a spindle onwhichsaid armature is mounted, a pair of thin, fiat spring membersresiliently supporting said spindle for movement in the direction of itsaxis, and means for supporting each end of both of said spring members,said means being supported from said pole pieces.

8. A ferromagnetic system for a transducer comprising an armature, aspindle on which said armature is mounted, and resilient means forsupporting the ends-of the spindle, said means being resilient only inthe direction of the longitudinal axis of the spindle.

9. A ferromagnetic system as claimed in claim 8 in which the spindleends are mounted between two flat, comparatively thin springs.

10. A ferromagnetic system as claimed in claim 8 in which the spindleends are mounted between springs provided with apertures in which thespindle ends are journaled.

11. A ferromagnetic system as claimed in claim 8 wherein the spindleends are journaled in springs which constitute two opposite sides of arectangular frame which has its other two sides secured tothe polepieces of the magnet system.

ALBERTUS ANTONY BARTELINK.

